The present invention relates to a composition and method for storing and releasing fuel gases such as hydrogen, and more particularly, to the use of lightly crosslinked high density polyethylene pellets to effectively store and release useful quantities of fuel gases.
It is well known that hydrogen is a very efficient and clean-burning fuel. However, the storage of hydrogen prior to its use has presented some difficulties. For example, hydrogen has physical characteristics which make it difficult to store in large quantities without taking up a significant amount of space. Currently, hydrogen is typically stored as a gas under high pressure in a large, heavy tank or vessel. It would be desirable to be able to store large quantities of hydrogen in smaller volumes at lower pressure and near room temperature.
One method which has been proposed for hydrogen storage includes the use of hollow microspheres filled with hydrogen gas. For example, hollow microspheres may be filled with hydrogen gas and stored in a chamber. When release of the hydrogen is desired, the hollow microspheres are moved from a storage chamber to a heated delivery and diffusion chamber. However, the use of hollow microspheres has several limitations. For example, because such microspheres are hollow, they cannot store a very high quantity of hydrogen. In addition, the spheres must have a minimum wall thickness to avoid collapse, which thickness often results in slower permeation and discharge rates.
While the storage of hydrogen has been proposed within other matrices such as amorphous hydrocarbon rubbers, the quantity of hydrogen which can be stored in such rubbers has been too low to allow practical use.
Accordingly, there is still a need in the art for a composition and method of effectively storing and releasing fuel gases such as hydrogen which allows a useful quantity of gas to be easily stored and released in a cost-efficient manner.